Abstract
Long freight trains up to 1500 m in length are currently not in regular operation in Europe. One of the important reasons for the same is high inter-wagon forces generated during the operation, especially when pneumatic (P-type) brake systems are used. For long trains with multiple locomotives at different positions along the train, radio communication with necessary fail-safe mechanisms can be used to apply the brakes. Long freight train operation on a given line is subjected to various attributes such as braking/traction scenarios, loading patterns, wagon geometries, brake-block materials, buffer types, track design geometries, etc., which are referred to as heterogeneities. The complex longitudinal train dynamics arising in the train due to various heterogeneities play a major role in determining its running safety. In this context, the maximum in-train force refers to the maximum force developed between any two wagons along the train during operation. The tolerable longitudinal compressive force is the maximum compressive force that can be exerted on a wagon without resulting in its derailment. Here, the authors adopt a bottom-up approach to model pneumatic braking systems and inter-wagon interactions in multibody simulation environments to study the complex longitudinal train dynamics behavior and estimate maximum in-train forces and tolerable longitudinal compressive forces, subjected to various heterogeneities. These two force quantities intend to facilitate a given freight train operation by providing guidelines regarding the critical heterogeneities, that currently limit its safe operation. In doing so, the authors propose the notion to have an operation-based approval for long freight trains using the simulations-based tool.
Highlights
For extensive rail freight transportation, one action to improve its capacity and efficiency is to run long trains
The in-train forces obtained from the workflow consists of the influences of heterogeneities ranging from the brake pneumatics to the vehicle- and track-based heterogeneities covered during the modeling process
Manoeuvres A and B from the braking scenarios above were considered for the simulation of pneumatics since the tractive operation in maneuver C is modeled in the in-train force tool
Summary
For extensive rail freight transportation, one action to improve its capacity and efficiency is to run long trains. Within a long freight train there can be various heterogeneities such as wagon dimensions, brake block materials, loading, buffer types, distance from the locomotive, and as a consequence different braking forces at a given instant. Each train is assumed to be composed of the same wagon type but with different payload distributions for the braking pneumatics and 1D in-train force MBS tools.
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